Buoyancy in Vessels and the Revolution of River Water
How narrower water bears less weight; whirling motion along river beds
The folio states that, at equal depth, narrower water sustains less weight upon itself, then illustrates the point with two pairs of vessels (labelled a, peso, aria, acqua) in which a floating body presses on the trapped air. Leonardo compares a smaller and a larger vessel, arguing that only the taller column of the larger vessel can push the air and its load upward as much as the weight presses down. A final remark on rivers holds that water has more revolution below its mid-height than above, because many obstacles lie on river beds while few rise near the surface. Faint mirror-script surrounds the two vessel drawings.
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Narrower water bears less weight
Of water of equal depth, that which is narrower will sustain less weight upon itself. This opening proposition frames the paired-vessel demonstration that follows.
Buoyant load in the two vessels of unequal width
In the smaller vessel (labelled a, peso, aria, acqua) the surrounding water does not press on the trapped air as much as the load set above it does. In the larger vessel the water stands so high above that air that it can push the air, together with the weight upon it, upward as strongly as the weight presses down.
Water revolves more below mid-height in rivers
Waters have more revolution from mid-height downward than from that mid-region upward, because of the many objects lying on the beds of rivers, while above there are few, save those set on the bottom that rise above the water.